Description:
<jats:title>Abstract</jats:title><jats:p>The increasing loss of biodiversity and the need to delay the sixth mass extinction on earth resulted in several international conventions aiming at protecting threatened species. Protection improves with increasing knowledge of the biology and ecology of these species. However, species numbers rapidly increase with the ongoing description of cryptic species, resulting in a lack of ecological knowledge for each of these species. We studied the nutritional ecology of three cryptic bat species of the <jats:styled-content style="fixed-case"><jats:italic>Myotis mystacinus</jats:italic></jats:styled-content> group using stable isotope analysis and molecular fecal analysis. Inter‐ and intraspecific variations were compared by calculating the isotopic and dietary niches for each species. We hypothesized (a) that all three species are generalists, but (b) that <jats:styled-content style="fixed-case"><jats:italic>M. mystacinus</jats:italic></jats:styled-content> and <jats:styled-content style="fixed-case"><jats:italic>Myotis brandtii</jats:italic></jats:styled-content> are more similar to each other than to <jats:italic>Myotis alcathoe</jats:italic>. Third we assumed that the occupied niches are intraspecifically more similar than interspecifically. We could show that the members of the <jats:styled-content style="fixed-case"><jats:italic>M. mystacinus</jats:italic></jats:styled-content> group differ in their nutritional ecology. Our data suggest that <jats:italic>M. alcathoe</jats:italic> is the most specialized species of the group, occupying a more distinct ecological niche compared to the other two species. Interestingly, the dietary and isotopic niche overlap was higher interspecifically than intraspecifically. Furthermore, considering our findings and those from other studies we illustrate implications for the conservation of these cryptic species.</jats:p>